This invention relates generally to fabric antennas, and, more specifically, to selective shielding of such antennas for the purpose of rendering them inoperative when necessary or desired.
Electronic signal antennas incorporated into fabric and used for transmission and reception of radio frequency signals, have been known and used for some time. Such antennas have been incorporated into articles of clothing, both for marking (tracking) the clothing article, as in retail sales protection, as well as for monitoring internal and external conditions in the vicinity of, or directly affecting, the wearer of the clothing article.
However, it has been noted that existing, prior art antennas of this type, and particularly xe2x80x9ctagxe2x80x9d antennas associated with articles of clothing, have not generally allowed the wearers to choose or control the active or inactive state of the antenna, and have not afforded protection from RF signals for wearers of such articles of clothing. In this regard, it may be desirable in certain applications, to protect sensitive wearers from unnecessary exposure to RF signals, and in the same or other applications it may be desirable to render the antenna inactive so as to avoid unintended transmission or reception of signals that may lead to accidents or misunderstandings. Certain antennas, and particularly xe2x80x9ctagxe2x80x9d antennas, do not incorporate xe2x80x9con-offxe2x80x9d switches for reasons attributable to their inherent design requirements, but nevertheless such antennas are often found in situations in which control of the antenna is desirable.
Accordingly, this invention provides methods and apparatus for rendering clothing-borne RF antennas selectively active or inactive. Further, this invention provides protection for wearers of clothing-borne RF antennas from unnecessary exposure to RF signals.
In the disclosed embodiments of this invention, fabric antennas are incorporated into articles of clothing such as coats, jackets and shirts, for example, in association with adjacent layers of different fabrics that provide electric field shielding with one type of fabric and RF shielding with another type of fabric. Both types of fabric are integrated directly into the structure of a wearable garment.
A first layer of shielding fabric is incorporated into the garment in a position lying between the antenna layer and the body of the wearer so as to protect the wearer from exposure to the RF field of the antenna.
This layer of shielding fabric in general can be made a structural part of the garment, immovable relative to the remainder of the garment, because it is not often necessary or desired to expose the human body to the RF signal field of an antenna carried by a garment other than one that is specifically intended for medical use.
A second layer of shielding fabric is positioned on a garment between the antenna and the outside environment in such a way that it can be displaced selectively, either to cover the antenna so as to shield it from signal transmission and/or reception, or to expose the antenna for normal use.
A feature of the invention is the incorporation of the displaceable layer of fabric into a portion of the garment that serves an ornamental or functional purpose independently of its shielding function.
Another feature of the invention is the provision of retention means for holding the displaceable fabric element in a position corresponding to either or both the active and the inactive conditions of the related antenna.
In accordance with at least one disclosed embodiment of the invention, the shielding layer of fabric reposes naturally in the xe2x80x9cactive antennaxe2x80x9d position until it is moved to, and retained affirmatively in, its xe2x80x9cinactivexe2x80x9d position.
These and other features and advantages of this invention will be made more apparent to those having skill in this art, by reference to the following specification considered in conjunction with the accompanying drawings, in which: